Optical phonons in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Pb</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mi>−</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Eu</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mi mathvariant="normal">Te</mml:mi></mml:math>epilayers and<mml:math xmlns:mml="http://www.w3.

Aigle, M.; Pascher, H.; Kim, Hyun-Jung; Tarhan, Enver; Mayur, A. J.; Sciacca, M. Dean; Ramdas, A. K.; Springholz, G.; Bauer, G.

doi:10.1103/physrevb.64.035316

Cited by 15 publications

(5 citation statements)

References 35 publications

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“…In solid solutions such as PbTe 1 - x Se x , atomic substitutions scatter short-wavelength phonons due to differences in mass, thereby reducing the lattice thermal conductivity. Low dimensional structures such as PbTe-based superlattice thin-films − and quantum dot superlattices − have been reported to produce improved thermoelectric figure of merit due to phonon confinement and enhanced phonon scattering that result in lower lattice thermal conductivity. It is now believed that low lattice thermal conductivity can also be achieved by nanocrystalline inclusions embedded in bulk materials. − …”

Section: Introductionmentioning

confidence: 99%

Nanostructures versus Solid Solutions: Low Lattice Thermal Conductivity and Enhanced Thermoelectric Figure of Merit in Pb_9.6Sb_0.2Te₁₀_-_xSe_x Bulk Materials

et al. 2006

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The series of Pb(9.6)Sb(0.2)Te(10)(-)(x)Se(x) compounds with different Se content (x) were prepared, and their structure was investigated at the atomic and nanosized regime level. Thermoelectric properties were measured in the temperature range from 300 to 700 K. The Pb(9.6)Sb(0.2)Te(10)(-)(x)Se(x) series was designed after the refinement of the single-crystal structure of Pb(3.82)Sb(0.12)Te(4) (Pb(9.6)Sb(0.3)Te(10); S.G. Pmm) by substituting isoelectronically in anion positions Te by Se. The Pb(9.6)Sb(0.2)Te(10)(-)(x)Se(x)() compounds show significantly lower lattice thermal conductivity (kappa(L)) compared to the well-known PbTe(1)(-)(x)Se(x) solid solutions. For Pb(9.6)Sb(0.2)Te(3)Se(7) (x = 7), a kappa(L) value as low as 0.40 W/m.K was determined at 700 K. High-resolution transmission electron microscopy of several Pb(9.6)Sb(0.2)Te(10)(-)(x)Se(x) samples showed widely distributed Sb-rich nanocrystals in the samples which is the key feature for the strong reduction of the lattice thermal conductivity. The reduction of kappa(L) results in a significantly enhanced thermoelectric figure of merit of Pb(9.6)Sb(0.2)Te(10)(-)(x)Se(x) compared to the corresponding PbTe(1)(-)(x)Se(x) solid solution alloys. For Pb(9.6)Sb(0.2)Te(3)Se(7) (x = 7), a maximum figure of merit of ZT approximately 1.2 was obtained at approximately 650 K. This value is about 50% higher than that of the state-of-the-art n-type PbTe. The work provides experimental validation of the theoretical concept that embedded nanocrystals can promote strong scattering of acoustic phonons.

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Section: Introductionmentioning

confidence: 99%

Nanostructures versus Solid Solutions: Low Lattice Thermal Conductivity and Enhanced Thermoelectric Figure of Merit in Pb_9.6Sb_0.2Te₁₀_-_xSe_x Bulk Materials

et al. 2006

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“…Recently, IR absorption measurements have been used for studying confined optical phonons in PbTe m / EuTe n superlattices. 58 The confined phonons manifest themselves as minima in the transmission spectrum. Under normal incidence only TO phonons are observed, while in oblique incidence both TO and LO phonons are seen.…”

Section: Single-and Multi-layers and Superlatticesmentioning

confidence: 99%

Raman spectroscopy of optical phonon confinement in nanostructured materials

Arora

Rajalakshmi

Ravindran

et al. 2007

J Raman Spectroscopy

361

294

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If the medium surrounding a nano-grain does not support the vibrational wavenumbers of a material, the optical and acoustic phonons get confined within the grain of the nanostructured material. This leads to interesting changes in the vibrational spectrum of the nanostructured material as compared to that of the bulk. Absence of periodicity beyond the particle dimension relaxes the zone-centre optical phonon selection rule, causing the Raman spectrum to have contributions also from phonons away from the Brillouin-zone centre. Theoretical models and calculations suggest that the confinement results in asymmetric broadening and shift of the optical phonon Raman line, the magnitude of which depends on the widths of the corresponding phonon dispersion curves. This has been confirmed for zinc oxide nanoparticles. Microscopic lattice dynamical calculations of the phonon amplitude and Raman spectra using the bond-polarizability model suggest a power-law dependence of the peak-shift on the particle size. This article reviews recent results on the Raman spectroscopic investigations of optical phonon confinement in several nanocrystalline semiconductor and ceramic/dielectric materials, including those in selenium, cadmium sulphide, zinc oxide, thorium oxide, and nano-diamond. Resonance Raman scattering from confined optical phonons is also discussed.

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“…One promising route to enhance ZT of PbTe based materials is to fabricate nanostructured PbTe, in hopes that the phonon scattering at grain boundaries could significantly reduce the lattice thermal conductivity [7]. Low dimensional structures of PbTe such as superlattice thin films [8][9][10][11][12][13], quantum dot superlattices [2,14], nanocrystals [15], hollow spheres [16], nanowires [15], nanoboxes [17] and hierarchical dendrites [18] have recently been reported.…”

Section: Introductionmentioning

confidence: 99%

Nanostructured PbTe compound synthesized by a simple chemical route

Cao

Zhu

Zhao

2010

Journal of Alloys and Compounds

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Optical phonons inPb1−xEuxTeepilayers and
M. Aigle
¹
,
H. Pascher
²
,
Hyun-Jung Kim
³

et al.

Cited by 15 publications

References 35 publications

Nanostructures versus Solid Solutions: Low Lattice Thermal Conductivity and Enhanced Thermoelectric Figure of Merit in Pb_9.6Sb_0.2Te₁₀_-_xSe_x Bulk Materials

Nanostructures versus Solid Solutions: Low Lattice Thermal Conductivity and Enhanced Thermoelectric Figure of Merit in Pb_9.6Sb_0.2Te₁₀_-_xSe_x Bulk Materials

Raman spectroscopy of optical phonon confinement in nanostructured materials

Nanostructured PbTe compound synthesized by a simple chemical route

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Optical phonons inPb1−xEuxTeepilayers andM. Aigle1, H. Pascher2, Hyun-Jung Kim3 et al.

Cited by 15 publications

References 35 publications

Nanostructures versus Solid Solutions: Low Lattice Thermal Conductivity and Enhanced Thermoelectric Figure of Merit in Pb9.6Sb0.2Te10-xSex Bulk Materials

Nanostructures versus Solid Solutions: Low Lattice Thermal Conductivity and Enhanced Thermoelectric Figure of Merit in Pb9.6Sb0.2Te10-xSex Bulk Materials

Raman spectroscopy of optical phonon confinement in nanostructured materials

Nanostructured PbTe compound synthesized by a simple chemical route

Contact Info

Product

Resources

About

Optical phonons inPb1−xEuxTeepilayers and
M. Aigle
¹
,
H. Pascher
²
,
Hyun-Jung Kim
³

et al.

Nanostructures versus Solid Solutions: Low Lattice Thermal Conductivity and Enhanced Thermoelectric Figure of Merit in Pb_9.6Sb_0.2Te₁₀_-_xSe_x Bulk Materials

Nanostructures versus Solid Solutions: Low Lattice Thermal Conductivity and Enhanced Thermoelectric Figure of Merit in Pb_9.6Sb_0.2Te₁₀_-_xSe_x Bulk Materials